Ditto for the Zerex G-05 antifreeze. It's approved for MB engines and costs around $6 per gal vs $11 per gallon for dealer antifreeze. Judging from the formlation both should be compatible with each other.
Coolant loss due to head gasket leaks can show up a couple of different ways. It can leak into the combustion chamber where it is burned, resulting in white smoke from the tailpipe. Or it can leak into the oil where it can turn the oil into a milkshake color. The second scenario is more serious. I suppose it can also leak to the outside of the engine, where it can be diagnosed just like any other coolant leak where you look for white deposits.
95 E320 Cabriolet, 131K